Projection exposure apparatus

ABSTRACT

Constant speed drive of a reticle and a wafer in a relative scanning direction and positioning of the reticle and the wafer are simultaneously performed with high precision by a slit scanning exposure scheme. A reticle side scanning stage for scanning a reticle relative to a slit-like illumination area in the relative scanning direction is placed on a reticle side base. A reticle side fine adjustment stage for moving and rotating the reticle within a two-dimensional plane is placed on the reticle side scanning stage. The reticle is placed on the reticle side fine adjustment stage. Constant speed drive and positioning of the reticle and a wafer are performed by independently controlling the reticle side scanning stage and the reticle side fine adjustment stage.

This is a continuation of application Ser. No. 08/139,803 filed Oct. 22,1993, now abandoned.

This is one of three ( 3 ) reissue applications directed to variousaspects of a projection exposure method and apparatus described in U.S.Pat. No. 5,477,304, which corresponds to U.S. patent application No.08/377,504 filed Jan. 25, 1995, which is a continuation of U.S. patentapplication No. 08/139,803 filed Oct. 22, 1993 (now abandoned). Thefirst filed reissue application is U.S. patent application No.08/994,758 filed Dec. 19, 1997. The other two reissue applications aredivisional applications of U.S. patent application No. 08/994,758. Theserial number and filing date of the two divisional reissue applicationsare: 09/779,686 filed Feb. 9, 2001; and 09/962,334 filed Sep. 26, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projection exposure apparatus usedwhen a semiconductor integrated circuit, a liquid crystal displaydevice, or the like is manufactured and, more particularly, to aprojection exposure apparatus for performing exposure by a scanningexposure scheme.

2. Related Background Art

When a semiconductor element, a liquid crystal display element, or thelike is to be manufactured by a lithographic process, a projectionexposure apparatus is used. This apparatus is designed to project apattern image of a photomask or reticle (to be generically referred toas a reticle hereinafter) on a photosensitive substrate through aprojection optical system. As such an apparatus, a projection scanningtype exposure apparatus is known, which is designed to simultaneouslyscan a reticle and a photosensitive substrate through a projectionoptical system.

As a conventional exposure apparatus of this type, an apparatus having areflecting projection optical system with X1 magnification is known. Inthis apparatus, a reticle stage for holding a reticle and a wafer stagefor holding a photosensitive substrate (to be referred to as a waferhereinafter) are coupled to a common movable column, and the reticle andthe wafer are scanned/exposed at the same speed. In such a scanningexposure apparatus (mirror projection aligner) with X1 magnification, ifa reticle pattern and a reticle pattern image projected on a wafer donot have a mirror-image relationship, an exposure operation is completedby one-dimensionally scanning an integral movable column in thewidthwise direction of arcuated slit illumination light while thereticle and the wafer are aligned and held on the movable column. As isapparent, with a projection system with X1 magnification in which areticle pattern and a reticle pattern image projected on a wafer have amirror-image relationship, the reticle stage and the wafer stage must bemoved in opposite directions at the same speed.

Another conventional scanning exposure apparatus incorporating arefracting element is also known. In this apparatus, while theprojecting magnification is increased or decreased with the refractingelement, both the reticle stage and the wafer stage are relativelyscanned at a speed ratio corresponding to a magnification. In this case,the projection optical system used is constituted by a combination of areflecting element and a refracting element or by only a refractingelement. An example of the reduction projection optical systemconstituted by a combination of a reflecting element and a refractingelement is disclosed in U.S. Pat. No. 4,747,678.

In addition, a method of performing step & scan exposure by using areduction projection optical system capable of full-field projection isdisclosed in U.S. Pat. No. 4,924,257. In this method, the reticle stagefor holding a reticle is designed to be movable in both the X directionas a scanning direction and the Y direction perpendicular to thescanning direction. Similarly, the wafer stage for holding a wafer isdesigned to be movable in both the X and Y directions. As disclosed inU.S. Pat. No. 5,004,348, the wafer stage and the reticle stage of anexposure apparatus based on the widely used conventional step and repeatscheme are also designed to be movable in both the X and Y directions. Aconventional scanning exposure apparatus may use the wafer and reticlestages of the above-described exposure apparatus of the step and repeatscheme so as to perform control to synchronously scan the two stages inthe X direction as the scanning direction. In this case, while a waferand a reticle are scanned in the X direction, the wafer stage and thereticle stage are finely moved within the X—Y plane to adjust thepositions of the wafer and the reticle in the X and Y directions and thedirection of rotation, thereby correcting the position deviation of thewafer relative to the reticle. Both the stages, however, are relativelyheavy. For this reason, they are poor in response characteristics andrequire complicated control. That is, in a conventional scanningexposure apparatus, it is difficult to perform constant speed drivecontrol in the scanning direction and simultaneously performhigh-precision control of positioning operations in the X and Ydirections and the direction of rotation.

As the above-described scanning exposure apparatus, a projectionexposure apparatus based on a scanning exposure scheme designed toperform stitching is known (U.S. Pat. No. 3,538,828). In this scanningexposure scheme designed to perform stitching, exposure light having apredetermined shape is radiated on a reticle, and the reticle and awafer are synchronously scanned, thereby performing exposure withrespect to an area corresponding to the first column on the wafer.

Subsequently, the reticle is replaced or is moved in the seconddirection perpendicular to the first direction of the illumination areaby a predetermined amount. The wafer is laterally shifted (stitching) ina direction conjugate to the second direction of the illumination area.Exposure light is radiated on the reticle again, and the reticle and thewafer are synchronously scanned, thus performing exposure with respectto an area corresponding to the second column on the wafer. With thisoperation, one shot area, on the wafer, which can be exposed can befurther increased. In this case, the moving amount of the wafer in thesecond direction is set such that the exposure areas of the first andsecond columns on the wafer overlap each other.

In such an exposure apparatus, high-precision overlapping of patternsand a reduction in illuminance irregularity at the overlapping portionbetween the areas of the first and second columns are required. However,these requirements are not satisfied by the conventional exposureapparatus.

The following problem is posed even in an exposure apparatus having aregular hexagonal illumination area such as the one disclosed in U.S.Pat. No. 4,924,257.

FIG. 14A shows an illumination area on a reticle in a projectionexposure apparatus of a stitching and slit scanning exposure scheme.Referring to FIG. 14A, exposure light from an illumination opticalsystem is radiated on a regular hexagonal illumination area 1 centeredon a position A. The illuminance in the illumination area 1 is uniform.By scanning the reticle in the −X direction with respect to theillumination area 1 at the position A at a constant speed V/β, theillumination area 1 relatively moves over the reticle along a trace 2Aand reaches a position B. The reticle is then moved in the Y directionto relatively move the illumination area 1 over the reticle along atrace 2B, thus causing the illumination area 1 to reach a position C.Thereafter, the reticle is scanned in the X direction at the constantspeed V/β to relatively move the illumination area 1 over the reticlealong a trace 2C.

FIG. 14B shows an exposure area on a wafer. Referring to FIG. 14B, aregular hexagonal exposure area 3 centered on a position AP is conjugateto the illumination area 1 at the position A on the reticle. The regularhexagonal exposure area 3 has two sides parallel to the Y direction.Letting R be the distance between two opposing vertexes of the regularhexagonal exposure area 3, and W be the distance between two opposingsides thereof, W=3^(1/2)R/2. When the wafer is scanned in the Xdirection with respect to the exposure area 3 at the position AP at aconstant speed V, the exposure area 3 relatively moves over the waferalong a trace 2AP and reaches a position BP. In this state, when thewafer is moved in the −Y direction by a distance 3R/4, the exposure area3 relatively moves over the wafer along a trace 2BP and reaches aposition CP. Thereafter, when the wafer is scanned in the −X directionat the constant speed V, the exposure area 3 relatively moved over thewafer along a trace 2CP.

The exposure area 3 which relatively moves along the trace 2AP and theexposure area 3 which relatively moves along the trace 2CP are scannedin the Y direction, i.e., the widthwise direction, such that theirisosceles triangle areas are superposed on each other in a connectionarea 4.

FIG. 15A shows a case where a regular hexagonal exposure area 3 isilluminated with a pulse laser beam from a pulse laser source. Referringto FIG. 15A, the exposure area 3 is an area inscribed in the contour ofa circular exposure area 7, of a projection, optical system, located ona wafer. Similar to equation (4) in the second embodiment, if the widthof the exposure area 3 in the X direction as a relative scanningdirection is represented by W, W=m·ΔL=m·T·V where T is the period ofpulse emission of a pulse laser source 52 in FIG. 6, ΔL is the distanceby which a wafer 14 is scanned in the X direction during one period T ina slit scanning exposure operation, and m is an integer larger than one.

FIG. 15A shows a case where m=8. Assume that an exposure point P0 islocated at an edge portion of the exposure area 3 when pulse emissionoccurs. The exposure point P0 is exposed to a pulse laser beam seventimes within the exposure area 3, and is exposed to a pulse laser beamtwice at the edge portion. In this case, since the energy exposed at theedge portion is ½ that exposed within the exposure area 3, energycorresponding to a total of eight pulses is radiated on the exposurepoint P0. Energy corresponding to a total of eight pulses is radiated onthe exposure point P0 regardless of the X-direction position of theexposure point P0 at the time of pulse emission.

Consider an exposure point through which an area 3a of the right-handisosceles triangle of the exposure area 3 passes. The distances by whichexposure points P1 to P8 shown in FIG. 15A pass through the area 3a ofthe isosceles are 8·ΔL to 1ΔΔL, respectively. Therefore, when the waferis scanned in the X direction with respect to the exposure area 3 (thefirst wafer scanning operation), energy corresponding to eight pulses isradiated on the exposure point P1, and energies corresponding to sevenpulses, six pulses, . . . are respectively radiated on the exposurepoints P2, P3, . . . .

When stitching of the wafer is performed, and the wafer is scanned inthe −X direction with respect to the exposure area 3 (the second waferscanning operation), energies corresponding to 0 to seven pulses arerespectively exposed on the exposure points P1 to P8. Therefore, energycorresponding to eight pulses is radiated on the exposure points P1 toP8, similar to the exposure point P0, by performing exposure twice uponstitching, as in the second embodiment.

However, at an exposure point P9 between the exposure points P4 and P5,even if slit scanning exposure is performed twice, radiated energyvaries. That is, as shown in FIG. 15B, pulse emission is performed whenthe exposure point P9 is at a position 8 in the first wafer scanningoperation, and pulse emission is performed when the exposure point P9 isat a position 9 in the second wafer scanning operation. Therefore,energy corresponding to nine pulses is radiated on the exposure pointP9.

In the case shown in FIG. 15C, in the first wafer scanning operation,pulse emission is performed when the exposure point P9 is at a position10, and in the second wafer scanning operation, pulse emission isperformed when the exposure point P9 is at a position 11. Therefore,energy corresponding to seven pulses is radiated on the exposure pointP9. That is, energy corresponding to seven to nine pulses is radiated onthe exposure point P9 depending on the timing of pulse emission.Consequently, at the connection portion 4 on the wafer, radiated energyirregularity, i.e., illuminance irregularity, is caused owing to a pulselaser beam.

SUMMARY OF THE INVENTION

It is the first object of the present invention to provide a scanningexposure apparatus which can drive a reticle and a wafer in apredetermined direction at a constant speed while controlling theirpositions with high precision. It is the second object of the presentinvention to realize a high-precision pattern overlapping operation andreduce illuminance irregularity at a connection portion, on aphotosensitive substrate, which is scanned and exposed twice by astitching operation in a scanning exposure apparatus designed to performa stitching operation.

In order to achieve the first object, according to the presentinvention, an exposure apparatus for exposing a pattern of a mask onto aphotosensitive substrate comprises the following components, as shown inFIG. 1:

synchronous scanning means (20, 23, 24, 27, 31) for synchronouslyscanning the mask (7) and the photosensitive substrate (14) whilemaintaining a predetermined speed ratio, when the pattern of the mask(7) is exposed onto the photosensitive substrate (14); and

adjusting means (21) for adjusting a position of the mask (7) within apredetermined reference plane parallel to a scanning direction of themask (7), independently of scanning of the mask (7) which is performedby the synchronous scanning means (20, 23, 24, 27, 31), during scanningexposure of the pattern of the mask (7) onto the photosensitivesubstrate (14).

According to the exposure apparatus of the present invention, when thepattern of the mask (7) is to be scanned/exposed on the photosensitivesubstrate (14), the synchronous scanning means (20, 23, 24, 27, 31)synchronously scans the mask (7) and the photosensitive substrate (14).The adjustment means (21) adjusts the position of the mask (7)independently of this scanning operation with respect to the mask (7)and the photosensitive substrate (14). Therefore, the position deviationof the mask (7) relative to the photosensitive substrate (14) during ascanning exposure operation can be corrected with high precision.

In addition, in order to achieve the first object, an exposure apparatusaccording to the present invention comprises the following components,for example, as shown in FIG. 1:

an illumination optical system (22) for radiating exposure light on apredetermined illumination area on a mask (7) on which a pattern to betransferred is formed;

a projection optical system (13) for projecting an image of a pattern onthe mask (7), irradiated with the exposure light, onto a photosensitivesubstrate (14);

a mask stage (20) for scanning the mask (7) relative to the illuminationarea in a direction perpendicular to an optical axis of the projectionoptical system (13);

a substrate stage (27) for scanning the photosensitive substrate (14)relative to the projected image of the pattern in a directionperpendicular to the optical axis of the projection optical system (13);

mask position detecting means (35) for detecting a position of the mask(7) within a plane perpendicular to the optical axis of the projectionoptical system (13);

substrate position detecting means (47) for detecting a position of thephotosensitive substrate (14) within a plane perpendicular to theoptical axis of the projection optical system (13);

adjustment means (21) for adjusting the position of the mask (7) withinthe plane perpendicular to the optical axis of the projection opticalsystem (13); and

control means (23) for causing the mask stage (20) and the substratestage (27) to synchronously scan when the pattern of the mask (7) isexposed on the photosensitive substrate (14), calculating a positiondeviation of the mask (7) relative to the photosensitive substrate (14)on the basis of detection signals from the mask position detecting means(35) and the substrate position detecting means (47), and causing theadjustment means (21) to adjust the position of the mask (7),independently of a scanning operation with respect to the mask (7) whichis performed by the mask stage (20), on the basis of the positiondeviation.

According to the exposure apparatus of the present invention, the drivesection for driving the mask (7) is divided into the mask stage (20),which is scanned in synchronism with the substrate stage (27), and theadjustment means (21) for adjusting the position of the mask (7), andthese two drive means are independently controlled. Therefore, as themask stage (20), for example, a heavy stage which can stably move at aconstant speed in a scanning operation is used. As the adjustment means(21), for example, a lightweight stage with high controllability isused, which is capable of fine movement in a translation direction and arotational direction. With this arrangement, scanning exposure can beperformed with excellent positional controllability.

In order to achieve the second object, an exposure apparatus accordingto the present invention comprises the following components, forexample, as shown in FIG. 6:

synchronous scanning means (23, 31, 66) for synchronously scanning amask (7) and a photosensitive substrate (14) in a predetermined firstdirection of an illumination area (43) while maintaining a predeterminedspeed ratio; and

illumination condition setting means (53, 55) for setting theillumination area (43) to be rectangular, and letting a light intensitydistribution of the illumination area (43) in a second directionperpendicular to the first direction have a trapezoidal shape so that amiddle portion of the distribution exhibits a substantially constantlight intensity, and two side portions of the distribution exhibit agradually decreasing light intensity.

According to the exposure apparatus of the present invention, the lightintensity distribution of the illumination area (43) in the seconddirection perpendicular to the first direction in which the mask (7) andthe photosensitive substrate (14) are relatively scanned has atrapezoidal shape. Consequently, as shown in FIG. 9B, the lightintensity distribution of an exposure area (43 P), which is located onthe photosensitive substrate (14) and conjugate to the illumination area(43), in the second direction (y direction) also has a trapezoidalshape. In addition, the width of the exposure area (43 P) in therelative scanning direction is constant. Therefore, exposure pointswhich are arranged on the photosensitive substrate (14) in the seconddirection and relatively scanned by the exposure area (43 P) areirradiated with exposure light corresponding to the same number ofpulses.

When the exposure area (43 P) is to be laterally shifted on thephotosensitive substrate (14) by stitching, areas (43 aP), 43 bP) inwhich the illuminance gradually decreases are superposed on each other,as shown in FIG. 10A. With this operation, at an exposure point Q3 on aconnection portion (80c) which is scanned twice by stitching, the sum ofa light intensity SA in the first scanning operation, and a lightintensity SB in the second scanning operation becomes equal to a lightintensity SC of a portion, of the trapezoidal light intensitydistribution, in which the light intensity is constant, as shown in FIG.10B. Therefore, the light intensity at an arbitrary point on theconnection portion (80c) on the photosensitive substrate (14) becomesalmost equal to the light intensity at an exposure point on anon-connection portion, thereby reducing the illuminance irregularity.

In addition, in order to achieve the second object, a projectionexposure apparatus according to the present invention comprises thefollowing components, for example, as shown in FIG. 6:

a pulse light source (52) for pulse-emitting exposure light;

an illumination optical system (53, 55, 58) for illuminating apredetermined illumination area (43) on a mask; on which a pattern to betransferred is formed, with the exposure light;

a projection optical system (13) for projecting an image of the pattern,irradiated with the exposure light, onto a photosensitive substrate(14);

synchronous scanning means (23, 31, 66) for synchronously scanning amask (7) and a photosensitive substrate (14) at least twice in apredetermined first direction of the illumination area (43) whilemaintaining a predetermined speed ratio;

substrate moving means (28) for moving the photosensitive substrate (14)in a second direction perpendicular to the first direction while firstand second scanning operations with respect to the mask (7) and thephotosensitive substrate (14) are performed by the synchronous scanningmeans (23, 31, 66); and

control means for controlling at least one of said pulse light source(52) and said synchronous scanning means (23, 31, 66) such that aposition of the photosensitive substrate (14) in the first direction atthe time when the light source (52) performs pulse emission, in thefirst scanning operation with respect to the photosensitive substrate(14) and the mask (7) coincides with that in the second scanningoperation.

According to the projection exposure apparatus of the present invention,as shown in FIG. 16A, when the photosensitive substrate (14) is scannedby, for example, a regular hexagonal exposure area (3), the position (8)of pulse emission of exposure light with respect to an arbitraryexposure point P9 on a connection area (4) in the first scanningoperation is the same as the position (12) of pulse emission of exposurelight in the second scanning operation. In the case shown in FIG. 16A,energy corresponding to eight pulses is radiated on the exposure pointP9. In the case shown in FIG. 16B, the timing of pulse emission isshifted from that in the case shown in FIG. 16A. However, similar to thecase shown in FIG. 16A, the position (10) of pulse emission of exposurelight with respect to the exposure point P9 in the first scanningoperation is the same as the position (13) of pulse emission of exposurelight in the second scanning operation. In the case shown in FIG. 16B,energy corresponding to eight pulses is also radiated on the exposurepoint P9. That is, by setting the photosensitive substrate at the sameposition in the scanning direction when the pulse light source performspulse emission in the first and second scanning operations, theconnection portion (4) which is scanned twice by stitching is alwaysirradiated with constant energy, thereby reducing the illuminanceirregularity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the overall arrangement of a projectionexposure apparatus according to the first embodiment of the presentinvention;

FIG. 2 is a plan view showing a reticle side stage system in FIG. 1;

FIG. 3 is a plan view showing a wafer side stage system in FIG. 1;

FIG. 4 is a flow chart showing a control method in a scanning exposureoperation in the first embodiment;

FIG. 5A is a plan view showing the relative positions of a reticle andan illumination area, and

FIG. 5B is a plan view showing the relative positions of a wafer and anexposure area in correspondence with FIG. 5A;

FIG. 6 is a view showing a projection exposure apparatus according tothe second embodiment of the present invention;

FIG. 7A is a plan view showing a slit-like illumination area on areticle 19 in FIG. 6, and

FIG. 7B is a graph showing the illuminance distribution of theillumination area;

FIG. 8 is a plan view showing a reticle pattern in the secondembodiment;

FIG. 9A is a plan view showing a slit-like exposure area on a wafer inthe second embodiment, and

FIG. 9B is a graph showing the illuminance distribution of the exposurearea;

FIG. 10A is a plan view showing an exposure area on a wafer; and

FIG. 10B is a graph showing the illuminance distribution of the exposurearea;

FIG. 11 is a plan view showing a trace of scanning exposure on a waferin the second embodiment;

FIGS. 12A and 12B are plan views other traces of scanning exposure onthe wafer in the second embodiment;

FIG. 13A is a plan view showing a modification of the illumination areaon a reticle, and FIG. 13B is a graph showing the illuminancedistribution of the modification of the illumination area;

FIG. 14A is a plan view showing a state in which relative scanning isperformed with respect to a regular hexagonal illumination area and areticle, and

FIG. 14B is a plan view showing a state in which relative scanning isperformed with respect to an exposure area on a wafer corresponding toFIG. 14A;

FIGS. 15A, 15B, and 15C are views for explaining illuminanceirregularity on a photosensitive substrate when a pulse emission typelight source is used to perform stitching and scanning exposure withrespect to a regular hexagonal exposure area; and

FIG. 16A is a plan view showing a positional relationship associatedwith pulse emission in a modification of the second embodiment of thepresent invention, and

FIG. 16B is a plan view showing another positional relationshipassociated with pulse emission.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A projection exposure apparatus according to the first embodiment of thepresent invention will be described below with reference to FIGS. 1 to5B.

FIG. 1 shows a projection exposure apparatus of a slit scanning exposurescheme according to this embodiment. Referring to FIG. 1, the X axis isdefined in a direction perpendicular to the drawing surface of FIG. 1within a plane parallel to a reticle 7, the Y axis is defined in adirection parallel to the drawing surface of FIG. 1, and the Z axis isdefined in a direction perpendicular to the X—Y plane. Assume that arelative scanning direction in slit scanning exposure is defined as theX direction.

An air guide elongated in the X direction is formed on a reticle sidebase 19 in a stage system for a reticle 7. A reticle side scanning stage20 is placed on the reticle side base 19 to be slidable in the Xdirection within the X—Y plane. A reticle side fine adjustment stage 21is placed on the reticle side scanning stage 20 so as to be translatedand rotated within the X—Y plane. The reticle 7 is held on the reticleside fine adjustment stage 21. In an exposure operation, a pattern areaof the reticle 7 is illuminated with exposure light IL from anillumination optical system 22 in the form of a rectangular illuminationarea (to be referred to as a slit-like illumination area hereinafter),and the reticle 7 is scanned in the X direction with respect to theslit-like illumination area. The illumination optical system 22 isconstituted by a light source, a shutter, an optical integrator, a fieldstop for setting the slit-like illumination area, a condenser lens, andthe like.

Three movable mirrors (only a movable mirror 33 is shown in FIG. 1) aredisposed on the reticle side fine adjustment stage 21. Three laserinterferometers (only a laser interferometer 35 is shown in FIG. 1)obtain the positions and rotational angles of the reticle side fineadjustment stage 21 within the X—Y plane by using laser beams reflectedby these three movable mirrors. The measurement results obtained bythese laser interferometers are supplied to a main control system 23.The main control system 23 controls the operation of the reticle sidescanning stage 20 through a relative scanning drive 24, and alsocontrols the operation of the reticle side fine adjustment stage 21through a fine adjustment drive 25.

In an exposure operation, a pattern in a slit-like illumination area onthe reticle 7 is projected/exposed on the wafer 14 through a projectionoptical system 13.

In a stage system for the wafer 14, an air guide elongated in the Xdirection is formed on a wafer side base 26, and a wafer side X stage 27is placed on the wafer side base 26 to be slidable in the X directionwithin the X—Y plane. A wafer side Y stage 28 is placed on the waferside X stage 27 so as to be movable in the Y direction within the X—Yplane. The wafer 14 is held on the wafer side Y stage 28. Although notshown, a Z stage, a leveling stage, and the like are arranged betweenthe wafer side Y stage 28 and the wafer 14. A stepping motor 29 isdisposed on one end of the wafer side X stage 27. The stepping motor 29drives the wafer side Y stage 28 in the Y direction through a ball screw30.

Three movable mirrors (only a movable mirror 45 is shown in FIG. 1) aredisposed on the wafer side Y stage 28. Three laser interferometers (onlya laser interferometer 47B is shown in FIG. 1) obtain the positions androtational angles of the wafer side Y stage 28 within the X—Y plane byusing laser beams reflected by these three movable mirrors. Themeasurement results obtained by these laser interferometers are alsosupplied to the main control system 23. In accordance with the threeposition measurement results, the main control system 23 controls theoperations of the wafer side X stage 27 and the wafer side Y stage 28through a drive 31.

FIG. 2 is a plan view showing a reticle stage system in FIG. 1.Referring to FIG. 2, two pairs of air guides 19a and 19b are formed, inrows, on the reticle side base 19 to extend in the X direction, andelectromagnets 32A and 32B are embedded on two sides of the air guides19a and 19b in rows in the X direction, respectively. Permanent magnetsare embedded in the rear surface of the reticle side scanning stage 20so that the reticle side scanning stage 20 is driven in the X directionby a linear motor scheme. A cooling function (e.g., a scheme ofcirculating a temperature-controlled gas or fluid) is provided for thereticle side scanning stage 20 to prevent heat generated by the linearmotor from being conducted to the reticle side fine adjustment stage 21.The reticle side fine adjustment stage 21 is placed on the reticle sidescanning stage 20. The movable mirror 33 having a reflecting surfaceperpendicular to the Y axis and elongated in the X direction is disposedon an end portion, of the reticle side fine adjustment stage 21, in theY direction. Movable mirrors 34A and 34B, each having a reflectingsurface perpendicular to the X axis, are disposed on two end portions,of the reticle side fine adjustment stage 21, in the Y direction.

The Y-axis laser interferometer 35 is fixed on the reticle side base 19to oppose the movable mirror 33. Similarly, an X-axis laserinterferometer 36A is fixed on the reticle side base 19 to oppose themovable mirror 34A. A laser interferometer 36B for rotation measurementis fixed on the reticle side base 19 to oppose the movable mirror 34B.Y-coordinate data RSy, X-coordinate data RSx, and rotational angle dataRSθ of the reticle side fine adjustment stage 21, which are respectivelyobtained by the Y-axis laser interferometer 35, the X-axis laserinterferometer 36A, and the rotation measurement laser interferometer36B, are supplied to the main control system 23 in FIG. 1.

Actuators 38, 40, and 42 are disposed on the reticle side scanning stage20 in FIG. 2. The actuators 38 and 40 finely adjust the reticle sidefine adjustment stage 21 in the X direction. The actuator 42 finelyadjusts the reticle side fine adjustment stage 21 in the Y direction.The positions at which the actuators 38 and 40 are in contact with thereticle side fine adjustment stage 21 are almost symmetrical with themovable mirrors 34A and 34B. The reticle side fine adjustment stage 21is biased toward the actuators 38, 40, and 42 through three pairs ofsprings 37A and 37B, 39A and 39B, and 41A and 41B. By adjusting thedisplacement amounts of the three actuators 38, 40, and 42, the reticleside fine adjustment stage 21 and the reticle 7 can be moved and rotatedwithin the X-Y plane.

A slit-like illumination area 43 elongated in the Y direction is formedon the reticle 7 by the exposure light IL. The optical axis of theY-axis laser interferometer 35 is set on a straight line which passes acenter 43A of the illumination area 43 and is parallel to the Y axis.When the reticle 7 is to be rotated, it must be rotated about the center43A of the illumination area 43 as an axis. However, when the reticle 7is scanned in the X direction, the position, of the reticle 7,corresponding to the center 43A changes. For this reason, the rotationalcenter of the reticle 7 is shifted in accordance with the position ofthe center 43A by adjusting the displacement amounts of the threeactuators 38, 40, and 42.

FIG. 3 is a plan view showing a wafer stage system. Referring to FIG. 3,two pairs of air guides 26a and 26b are formed, in rows, on the waferside base 26 to extend in the X direction. Electromagnets 44A and 44Bare embedded on two sides of the air guides 26a and 26b in rows in the Xdirection, respectively. The wafer side X stage 27 is placed on the airguides 26a and 26b. The wafer side Y stage 28 is placed on the waferside X stage 27. Permanent magnets are embedded in the rear surface ofthe wafer side X stage 27 so that the wafer side X stage 27 is driven inthe X direction with high precision by a linear motor scheme. A coolingfunction is provided for the wafer side X stage 27 to prevent heatgenerated by the linear motor from being conducted to the wafer side Ystage 28. In addition, two pairs of air guides 27a and 27b are formed,in rows, on the wafer side X stage 27 to extend in the Y direction. Thewafer side Y stage 28 is driven along these air guides 27a and 27b inthe Y direction by the stepping motor 29.

The movable mirror 45 having a reflecting surface which is perpendicularto the Y axis and is elongated in the X direction is disposed on an endportion, of the wafer side Y stage 28, in the Y direction. A movablemirror 46 having a reflecting surface which is perpendicular to the Xaxis and is elongated in the Y direction is disposed on an end portion,of the wafer side Y stage 28, in the X direction. A Y-axis measurementlaser interferometer 47A and the rotation measurement laserinterferometer 47B are fixed on the wafer side base 26 so as to opposethe movable mirror 45 and be separated from each other by the Xdirection by a predetermined distance. Similarly, an X-axis measurementlaser interferometer 48 is fixed on the wafer side base 26 so as tooppose the movable mirror 46. Y-coordinate data WSy, X-coordinate dataWSx, and rotational angle data WSθ of the wafer side Y stage 28, whichare respectively obtained by the Y-axis measurement laser interferometer47A, the X-axis laser interferometer 48, and the rotation measurementlaser interferometer 47B, are supplied to the main control system 23 inFIG. 1.

In this case, the optical axis of the projection optical system 13 islocated at the intersection between the optical axis of the laserinterferometer 47A and the optical axis of the laser interferometer 48.An off-axis alignment system 49 is arranged on the side, of theprojection optical system 13, in the Y direction. The detection centerof the alignment system 49 is located on the optical axis of the laserinterferometer 47B, and the optical axis of the laser interferometer 48is located on a straight line which passes the detection center of thealignment system 49 and is parallel to the X axis. An area of aconjugate image formed on the wafer 14 by the projection optical system13 and corresponding to the slit-like illumination area 43 shown in FIG.2 is a slit-like exposure area 43 P elongated in the Y direction. Notethat since the Y-direction side portions of the illumination area 43 areslightly vignetted by the light-shielding portion of the reticle 7, theY-direction length of the exposure area 43 P is smaller than that of theconjugate image of the illumination area 43 itself.

A method of controlling the reticle stage system and the wafer stagesystem in a slit scanning exposure operation in this embodiment will bedescribed next.

In general, a pattern of the reticle 7 is reduced/projected of the wafer14. This is because reduction projection is advantageous in managing thedimensions of a pattern of the reticle 7, dust, and the like. If,however, the projecting magnification of the projection optical system13 is set to be β, the reticle side stage must be driven at high speedby an amount corresponding to a multiple of the reciprocal of theprojecting magnification D with respect to the wafer side stage in aslit scanning exposure operation. In many cases, therefore, theprocessing performance with respect to relative scanning and stagecontrol in an exposure operation depends on the drive performance of thereticle side stage.

The main control system 23 in FIG. 1 issues an X-direction drive commandODWx and a Y-direction drive command ODWy to the drive 31 to move thewafer 14 in the X and Y directions, respectively. The X- and Y-directiondrive commands ODWx and ODWy serve to control the operations of linearmotors for the wafer side X stage 27 and the stepping motor 29,respectively. The main control system 23 issues a first drive commandODR1 to the scanning drive 24 to move the reticle 7 in the X-directionas a relative scanning direction, and also issues a second drive commandODR2 to the fine adjustment drive 25 to move and rotate the reticle 7within the X—Y plane. The first drive command ODR1 controls theoperation of the linear motor for the reticle side scanning stage 20,and the second drive command ODR2 controls the operations of the threeactuators 38, 40, and 42 (see FIG. 2) of the reticle side fineadjustment stage 21.

A control method will be described below with reference to the flowchart in FIG. 4 and FIGS. 5A and 5B.

FIG. 5A shows the relative positional relationship between the reticle 7and the slit-like illumination area 43. FIG. 5B shows the relativepositional relationship between the wafer 14 and the slit-like exposurearea 43 P. Assume that reduced pattern images of the reticle 7 aresequentially exposed on two adjacent shot areas 50A and 50B on the wafer14. For the sake of descriptive convenience, assume that the center ofthe illumination area 43 in FIG. 5A is located at a central position Aof the reticle 7, and the center of the exposure area 43 P in FIG. 5B islocated at a central position AP of the first shot area 50A in aninitial state. In this case, the relative position and rotational angledifferences between the reticle 7 and the wafer 14 are 0. Furthermore,assume that the reticle 7 is scanned in the X direction at a speed V/β,and the wafer 14 is scanned in the −X direction at a speed V in theinitial state. The flow of processing shifts from this initial state tostep 101 in FIG. 4.

In step 101 in FIG. 4, the main control system 23 in FIG. 1 drives thewafer side X stage 27 in the −X direction at the speed V, and drives thereticle side scanning stage 20 in the X direction at the speed V/β. Inorder to drive the wafer side X stage 27 at a constant speed, the maincontrol system 23 samples the differential value of the X-coordinatedata WSx supplied from the laser interferometer 48 and issues theX-direction drive command ODWx to make the differential value constantso as to correspond to the speed V. Similarly, in order to drive thereticle side scanning stage 20 at a constant speed, the main controlsystem 23 samples the differential value of the X-coordinate data RSxsupplied from the laser interferometer 36A and issues the first drivecommand ODR1 to make the differential value constant so as to correspondto the speed V/β.

In addition, the main control system 23 performs positional control ofthe wafer side Y stage 28 and the reticle side fine adjustment stage 21.More specifically, the main control system 23 detects the X-coordinatedata WSx associated with the wafer 14 and the X-coordinate data RSxassociated with the reticle 7, and samples (WSx/β+RSx) on the basis ofthese data. Similarly, the main control system 23 samples (WSy/β+RSy) onthe basis of the Y-coordinate data WSy associated with the wafer 14 andthe Y-coordinate data WRy associated with the reticle 7; and (WSθ+RSθ)on the basis of the rotational angle data RSθ associated with the wafer14 and the rotational angle data RSθ associated with the reticle 7.

Subsequently, the main control system 23 issues the Y-direction drivecommand ODWy and the second drive command ODR2 to the drives 31 and 25,respectively, to perform position control such that these three databecome predetermined reference values, respectively. These threereference values are predetermined on the basis of the design coordinatevalues of the respective shots arranged on a wafer, and are stored in astorage unit in the main control system 23. When each slot is to beexposed, the positions of the wafer and the reticle are controlled onthe basis of the three reference values corresponding to each shot andthe three sampled data.

With this operation, the center of the illumination area 43 shifts fromthe position A to the position B located outside the pattern area of thereticle 7 in FIG. 5A, and the center of the exposure area 43 P shiftsfrom the position AP to the position BP located outside the first shotarea 50A of the wafer 14 in FIG. 5B, thus completing the first slitscanning exposure operation.

In step 102, the main control system 23 drives the wafer side X stage 27such that the stage 27 is decelerated temporarily and is accelerated inthe X direction, and also drives the wafer side Y stage 28 such that thestage 28 is accelerated temporarily and is decelerated in the Ydirection. Meanwhile, the main control system 23 decelerates the reticleside scanning stage 20 and resets the reticle side fine adjustment stage21 to the initial position. With this operation, the center of theillumination area 43 shifts from the position B to a position C locatedfarther outside than the position B and stops thereat in FIG. 5A, andthe center of the exposure area 43 P shifts from the position BP to aposition CP located outside the second shot area 50B of the wafer 14 inFIG. 5B. At this position CP, the wafer side X stage 27 has alreadystarted constant speed scanning in the X direction.

In step 103, the main control system 23 drives the wafer side X stage 27in the X direction at the speed V. In addition, since the position ofthe wafer side Y stage 28 is fluctuating owing to the acceleration anddeceleration of the wafer side Y stage 28 in step 102, the main controlsystem 23 stabilizes the position of the wafer side Y stage 28 throughthe stepping motor 29. Meanwhile, the main control system 23 acceleratesthe reticle side scanning stage 20 in the −X direction. With thisoperation, the center of the illumination area 43 shifts from theposition C to a position D closer to the reticle 7 in FIG. 5A, and thecenter of the exposure area 43 P shifts from the position CP to aposition DP closer to the second shot area 50B in FIG. 5B. At theposition D, the reticle side scanning stage 20 has already started tomove in the X direction at the constant speed V/β. Therefore, thescanning speed of the reticle 7 relative to the wafer 14 has reached thedesign value.

In step 104, the main control system 23 drives the wafer side X stage 27in the X direction at the speed V, and drives the reticle side scanningstage 20 in the −X direction at the constant speed V/β. In addition, themain control system 23 performs positional control of the wafer side Ystage 28 and the reticle side fine adjustment stage 21. Morespecifically, similar to step 101, the main control system 23 samples(WSx/β+RSx), (WSy/β+RSy), and (WSθ+RSθ) from the coordinate positions ofthe wafer 14 and the reticle 7. The main control system 23 then issuesthe Y-direction drive command ODWy and the second drive command ODR2 tothe drives 31 and 25, respectively, and performs position control suchthat these three data become predetermined values, respectively.

In this manner, the positions of the reticle 7 and the wafer 14 arecontrolled. At this time, the center of the illumination area 43 is at aposition E located outside the pattern area of the reticle 7, as shownin FIG. 5A, and the center of the exposure area 43 P is at a position EPlocated outside the second shot area 50B of the wafer 14, as shown inFIG. 5B.

In step 105, when constant speed drive of the reticle 7 and the wafer 14and coordinate position correction thereof are completed, the center ofthe illumination area 43 is at a position F located immediately beforethe pattern area of the reticle 7, as shown in FIG. 5A, and the centerof the exposure area 43 P is at a position FP immediately before thesecond shot area 50B of the wafer 14, as shown in FIG. 5B.

With the same control as that performed in step 101, the illuminationarea 43 relatively scans the reticle 7 up to its central position G, asshown in FIG. 5A, and the exposure area 43 P relatively scans the secondshot area 50B of the wafer 14 up to its central position GP, as shown inFIG. 5B. Thereafter, by repeating the processing in step 101 and thesubsequent steps, patterns of the reticle 7 are exposed on the secondshot area 50B and the next shot area of the wafer 14.

As described above, according to the first embodiment, the stage systemon the reticle 7 side is divided into the reticle side scanning stage 20and the reticle side fine adjustment stage 21, and these stages can beindependently driven. With this arrangement, while the reticle 7 and thewafer 14 are driven at constant speeds, respectively, the coordinatepositions of the reticle 7 and the wafer 14 can be easily and quicklycorrected. Therefore, a pattern image of the reticle 7 can be exposed oneach shot area of the wafer 14 without distortion.

Provided that the weights of the reticle side scanning stage 20 and thereticle side fine adjustment stage 21 are respectively represented by M1and M2, a relative scanning linear motor drives the stages 20 and 21with a weight (M1+M2). In contrast to this, since the actuators 38, 40,and 42 shown in FIG. 2 drive the reticle side fine adjustment stage 21with the weight M2, they exhibit excellent response characteristics incorrection of the position deviation. Assume that when an acceleration ais applied to the reticle side fine adjustment stage 21 on the reticleside scanning stage 20, the acceleration of the reticle side scanningstage 20, which acts on the reticle side scanning stage 20 (i.e., thereaction of the acceleration a) is represented by b. In this case, thefollowing equation can be established:M2·a=(a1+M2)b   (1)

Therefore, the acceleration b is lower than the acceleration a, andpositional control of the reticle side fine adjustment stage 21 hardlyaffects the constant speed scanning operation of the reticle sidescanning stage 20, thus realizing stable speed control.

A projection exposure apparatus according to the second embodiment ofthe present invention will be described next with reference to FIGS. 6to 16B. In this embodiment, the present invention is applied to aprojection exposure apparatus of a stitching and slit scanning exposurescheme, which apparatus includes a pulse emission type laser source.

FIG. 6 shows the overall arrangement of the projection exposureapparatus of the second embodiment. The second embodiment has almost thesame arrangement as that of the first embodiment except for theillumination optical system 22 and the stage system for a reticle in thefirst embodiment. Therefore, the same reference numerals in FIG. 6denote the parts having the same functions as in FIG. 1, and adescription thereof will be omitted.

Referring to FIG. 6, a laser beam LB emitted from a pulse laser source52 such as an excimer laser is incident on an illumination optimizingoptical system 53 constituted by a beam expander an optical integrator,and an aperture stop, a relay lens, and the like. A pulse laser beam ILas exposure light emerging from the illumination optimizing opticalsystem 53 is reflected by a deflecting mirror 54 to be incident on afield stop 55. The pulse laser beam IL passing through the aperture ofthe field stop 55 illuminates a reticle 7 with uniform illuminancethrough a relay lens 56, a deflecting mirror 57, and a condenser lens58. The plane where the field stop 55 is arranged is conjugate to thepattern formation surface of the reticle 7. The shape of a slit-likeillumination area 43 on the pattern formation surface of the reticle 7is set by the aperture of the field stop 55.

The reticle 7 is held on a reticle stage 61. Movable mirrors 62 areattached to the reticle stage 61 in the X direction (a lateral directionparallel to the drawing surface of FIG. 6) and the Y direction (adirection perpendicular to the drawing surface of FIG. 6), respectively.The reticle stage 61 and the movable mirrors 62 are held such that theycan be moved along a guide 63 with the X—Y plane and can be moved in theX direction at a constant speed. A drive 66 is connected to the reticlestage 61 to move the stage 61 in the X and Y directions and perform finerotation for yawing correction. Laser beams from a laser interferometer64 fixed to the guide 63 are reflected by the movable mirrors 62 so thatthe X- and Y-direction positions of the reticle 7 and its yawing amountare constantly measured by the laser interferometer 64. The measurementdata are supplied to a main control system 23. The main control system23 supplies a control signal S₁ to the drive 66 to control the movementof the reticle 7, and also outputs a control signal S₂ to a laser sourcecontrol system 51 to control the emission of the pulse laser source 52.The main control system 23 includes a storage unit 23a.

FIG. 7A shows the slit-like rectangular illumination area 43 on thereticle 7. The illumination area 43 is inscribed in the contour of acircular area conjugate to the maximum exposure field of a projectionoptical system 13. The illumination area 43 has a length LP (=L+2M) inthe Y direction and a width D in the X direction. When the reticle 7 isscanned in the X direction, a pulse laser beam within the illuminationarea 43 sequentially illuminates a pattern area wider than theillumination area 43 on the reticle 7. As shown in FIG. 7B, according toa light intensity distribution (to be referred to as an illuminancedistribution hereinafter) S in the Y direction within the illuminationarea 43, the light intensity is constant in a central area having alength L, and decreases almost linearly to 0 in side areas 43a and 43b,each having a length M. That is, the illuminance distribution S of theillumination area 43 in the Y direction perpendicular to the relativescanning direction has a trapezoidal shape. In order to obtain such atrapezoidal illuminance distribution, the aperture of the field stop 55in FIG. 6 may be set in a defocus state in the longitudinal direction.Alternatively, a trapezoidal illuminance distribution can be obtained byarranging an ND filter plate or the like, whose transmittance linearlychanges, in the field stop 55 or the illumination optimizing opticalsystem 53.

FIG. 8 shows the reticle 7 in FIG. 6. Referring to FIG. 8, a patternarea 75 having a width LT in the Y direction is formed on the patternformation surface of the reticle 7. A circuit pattern to be transferredonto a wafer is formed in this pattern area 75. A forbidden zone 76,consisting of a light-shielding portion having a width M or more, isformed on outer peripheral portions of the pattern area 75 in the Ydirection. In the second embodiment, the pattern area 75 is scannedtwice in the X direction with the slit-like illumination area 43 totransfer a pattern of the pattern area 75 onto the wafer. For example, apattern of a substantially right half area 75a is transferred onto thewafer by the first scanning operation, and a pattern of a substantiallyleft half area 75b is transferred onto the wafer by the second scanningoperation.

In this case, a left side portion of the area 75a and a right sideportion of the area 75b are superposed on each other at a connectionarea 75c having the width M in the Y direction, and the connectionportion 75c is scanned by the area 43a or 43b in which the lightintensity (illuminance) of the illumination area 43 gradually decreases.With this operation, the illuminance distribution of the connectionportion 75c is made uniform, and the position deviation of a transferredpattern can be prevented. In addition, in order to make the illuminancein the pattern area 75 constant, no area at an end portion of thepattern area 75 in the Y direction is scanned by the area 43a or 43b inwhich the illuminance of the illumination area 43 gradually decreases.Since the Y-direction width of the area, in the illumination area 43, inwhich the illuminance is constant is represented by L, and the Ydirection width of the pattern area 75 is represented by LT, theY-direction width M of the area 43a or 43b in which the illuminancegradually decreases to 0 is given by:M=LT−2·L   (2)

In general, the pattern area 75 is scanned n times in the X direction bythe illumination area 43 to transfer a pattern of the pattern area 75onto a wafer 14. In order to prevent the formation of an area which isilluminated only with the area 43a or 43b in which the illuminancegradually decreases, the width M of the area 43a or 43b in which theilluminance gradually decreases may be set as follows:M=(n·LP−LT)/(n+1)   (3)

FIG. 9A shows a slit-like rectangular exposure area 43 P on the wafer 14in FIG. 6. The exposure area 43 P is conjugate to the illumination area43 on the reticle 7 in FIG. 7A. In this case, since the projectingmagnification of the projection optical system 13 is β, the X- andY-direction widths of the exposure area 43 P are β·D and β·LP,respectively. In addition, as shown in FIG. 9B, in areas 43 aP and 43bP, of the exposure area 43 P, located at two ends and having a widthβ·M in the Y direction, illuminance S decreases almost linearly to 0.The illuminance distribution of the exposure area 43 P in the Ydirection perpendicular to the relative scanning direction has atrapezoidal shape.

The condition for the width β·D of the exposure area 43 P in the Xdirection as the relative scanning direction will be described next. Inthis case, provided that the pulse emission period (i.e., the reciprocalof an emission frequency f) of the pulse laser source 52 in FIG. 6 is T,and the distance by which the wafer 14 is scanned in the X direction inone period T during an slit scanning exposure operation is ΔL, theX-direction width Δ·D of the exposure area 43 P is set to be an integermultiple of the distance ΔL. In addition, if the scanning speed of thewafer 14 in the X direction is represented by V, then the distance ΔL isT·V. That is, the following equation can be established, providing thatm is an integer of one or more:β·D=m·ΔL=m·T·V   (4)

FIG. 9A shows a case where β·D=4·ΔL. In this case, for example, anexposure point Q0 which is present at an edge portion of the exposurearea 43 P when pulse emission occurs is irradiated with a pulse laserbeam corresponding to three pulses within the exposure area 43 P, and isirradiated with a pulse laser beam corresponding to two pulses at theedge portion of the exposure area 43 P. Letting ΔE be the energyradiated on an exposure point inside the exposure area 43 P by one pulseemitting operation, energy represented by 4·ΔE (=ΔE/2+3·ΔE+ΔE/2) isradiated on the exposure point Q0. In addition, as shown in FIG. 9A,energy represented by 4·ΔE is radiated on an exposure point Q1, on thewafer, which is present inside the edge portion of the exposure area 43P when pulse emission occurs, and energy represented by 4·ΔE is radiatedon an exposure point Q2, on the wafer, which is present outside the edgeportion of the exposure area 43 P when the pulse emission occurs. Asdescribed above, according to the second embodiment, the same pulselaser beam corresponding to m pulses is radiated on all the exposurepoints, on the wafer, which are scanned by the exposure area 43 P.Therefore, a constant illuminance distribution is set at the exposurepoints which are scanned by the area, of the exposure area 43 P, inwhich the illuminance is constant.

Although energy corresponding to m pulses is radiated on exposure pointswhich are scanned once by the two side areas 43 aP and 43 bP of theexposure area 43 P, the radiated energy is lower than that radiated onthe other exposure points. However, as described above, in the secondembodiment, since a connection portion is scanned twice by the areas 43aP and 43 bP in a stitching operation, energy represented by m·ΔE isalso radiated on each exposure point of the connection portion.Therefore, the same amount of energy is radiated on all the exposurepoints on the wafer, preventing illuminance irregularity.

An example of stitching and slit scanning exposure in the secondembodiment will be described next. Referring to FIG. 6, while theslit-like illumination area 43 on the reticle 7 is illuminated with thepulse laser beam IL, the main control system 23 scans the reticle 7 inthe −X direction at the constant speed V/β through the drive 66 and thereticle stage 61. In synchronism with this scanning operation, the maincontrol system 23 scans the wafer 14 in the X direction at the constantspeed V through a drive 31. In this case, the main control system 23obtains the coordinate position (RSx,RSy) of the reticle 7 and thecoordinate position (WSx,WSy) of the wafer 14 at the time when, forexample, a predetermined alignment mark on the reticle 7 coincides witha predetermined alignment mark on the wafer 14, on the basis ofmeasurement values obtained by a laser interferometer 64 and a laserinterferometer 47. Similar to the first embodiment, the main controlsystem 23 then calculates (SWx/β+RSx), (WSy/β+RSy), and (WSθ+RSθ), andstores these values as reference values in the storage unit 23a inadvance. In addition, the main control system 23 obtains these threereference value for each shot exposed on the wafer in advance, andstores them in the storage unit 23a. The main control system 23 controlsthe coordinate positions of the wafer 14 and the reticle 7 through thedrives 66 and 31 such that the three data (WSx/β+RSx), (WSy/β+RSy), and(WSθ+RSθ) sampled during a relative scanning operation with respect tothe wafer 14 and the reticle 7 coincide with the above-mentionedreference values.

With this operation, as shown in FIG. 8, on the reticle 7 side, theslit-like illumination area 43 relatively scans the right area 75a ofthe pattern area 75 along a trace 77. In addition, as shown in FIG. 10A,on the wafer side 28, the slit-like exposure area 43 P relatively scansa left area 80a of an exposure area 80 along a trace 77 P.

When the first slit scanning exposure operation is completed, thereticle 7 is moved in the Y direction by stitching so as to move theillumination area 43 to an upper left position in the pattern area 75along a trace 78, as shown in FIG. 8. Referring to FIG. 10A, a slit-likeexposure area 20 P is moved to a lower right position in the exposurearea 80 along a trace 78 P by moving the wafer 14 in the −Y direction.Thereafter, the reticle 7 is scanned at the speed V/β in the Xdirection, and the wafer 14 is scanned at the speed V in the −Xdirection, thereby performing the second slit scanning exposureoperation. As a result, as shown in FIG. 8, on the reticle 7 side, theslit-like illumination area 43 relatively scans the left area 75b of thepattern area 75 along a trace 79. In addition, as shown in FIG. 10A, onthe wafer 14 side, the slit-like exposure area 43 P relatively scans theright area 80b of the exposure area 80 along a trace 79 P.

As shown in FIG. 8, at the connection portion 75c of the pattern area 75of the reticle 7, exposure is performed twice by the left and rightareas 43a and 43b, of the illumination area 43, in which the illuminancedecreases, with the first and second scanning operations. Therefore, themain control system 23 controls the position of the reticle 7 such thatthe moving amount of the reticle 7 in the Y direction in a stitchingoperation becomes (LP−M). Similarly, the main control system 23 controlsthe position of the wafer 14 such that the moving amount of the wafer 14in the −Y direction in a stitching operation becomes (LP−M)/β.

With this control, as shown in FIG. 10A, at a connection portion 80c, ofthe exposure area 80 of the wafer 14, located at a middle position inthe Y direction, exposure is performed twice by the right and left areas43 ap and 43 bp, of the slit-like exposure area 43 P, in which theilluminance decreases. For example, at an exposure point Q3 inside theconnection portion 80c, the illuminance in the first exposure operationbecomes an illuminance SA in FIG. 10B; and the illuminance in the secondexposure operation, an illuminance SB. As shown in FIG. 9B, since theilluminances of the areas 43 aP and 43 bP in the Y directionsymmetrically and linearly decrease to 0, the sum of the illuminances SAand SB in FIG. 10B becomes equal to an illuminance SC obtained whenexposure is performed by using the area, of the exposure area 43 P, inwhich the illuminance is constant.

As has been described above, all the exposure points which are scannedby the exposure area 43 P once are irradiated with a pulse lasercorresponding to m pulses. The exposure point Q3 inside the connectionportion 80c is irradiated with the same amount of energy as thatradiated on an exposure point which is scanned once by two scanningoperations of the exposure area 43 P (i.e., an exposure point outsidethe connection portion). Therefore, the illuminances at all the exposurepoints on the wafer 14 are made uniform. In addition, at an exposurepoint inside the connection portion 80c, the number of pulses radiatedin two scanning operations is 2 m, which is twice that radiated at anexposure point outside the connection portion. Therefore, at theconnection portion 80c, especially variations in the energy of a pulselaser beam for each pulse and the influences of speckles are reduced.More specifically, at the connection portion 80c, the variations inilluminance due to variations in the energy of a pulse laser beam foreach pulse are reduced to ½^(1/2) the variations at a non-connectionportion.

In the second embodiment, when slit scanning exposure is to be performedwith respect to the area 80a on the wafer 14 shown in FIG. 10A, the maincontrol system 23 stores the differences between the above-mentionedthree data (WSx/β+RSx), (WSy/β+RSy), and (WSθ+RSθ) and the correspondingreference values in the storage unit 23a. When a pulse laser beamcorresponding to m pulses is radiated on an arbitrary exposure point onthe wafer 14 by the first scanning operation, the main control system 23monitors each difference in synchronism with each pulse emittingoperation. These differences cause intra-shot distortion at theconnection portion 80c on the wafer 14. Therefore, when exposure is tobe performed with respect to the area 80b on the wafer 14 by the secondscanning operation, the main control system 23 controls the coordinatepositions of the reticle 7 and the wafer 14 through the drives 66 and 31such that the monitored differences coincide with the readoutdifferences. With this operation, the pattern overlapping precision atthe connection portion 80c on the wafer 14 is greatly improved.

In general, if the positioning precisions of the reticle stage 61 andwafer stages (27 and 28) in the X and Y directions are respectivelyrepresented by Δx and Δy, overlapping errors at the connection portion80c are respectively represented by 2^(1/2)Δx and 2^(1/2)Δy. In contrastto this, according to the method of the second embodiment, theoverlapping errors are only Δx and Δy because the positions of thereticle 7 and the wafer 14 in exposing the area 80b by the secondscanning operation are controlled in accordance with shot distortioncaused in exposing the area 80a by the first scanning operation.

A method of exposing the entire exposure surface of the wafer 14 will bedescribed next. Consider a case where the stitching and slit scanningexposure operation described in the second embodiment is applied to thisexposure method. As shown in FIG. 11, exposure is sequentially performedwith respect to adjacent areas 80-1a, 80-1b, 80-2a, 80-2b, . . . ,80-4a, and 80-4b by the slit scanning exposure method. According to thisscanning method, a pattern of the pattern area 75 can be transferredonto the wafer 14 in a short period of time, and hence the transferoperation is not easily influenced by the expansion of the wafer 14 andthe like. In contrast to this, the precision at the connection portionmay deteriorate depending on the characteristics in the scanningdirection. For this reason, the reticle 7 must be moved, along the trace78, in the Y direction with respect to the illumination area 43 in FIG.8, at a high speed.

According to another exposure method, as shown in FIGS. 12A and 12B, forexample, only the right half area 75a of the pattern area 75 of thereticle 7 is continuously exposed on a corresponding area on the wafer14. Thereafter, only the left half area 75b of the pattern area 75 iscontinuously exposed on a corresponding area on the wafer 14. In thismethod, as shown in FIG. 12A, exposure is performed first with respectto the areas 80-1a, 80-2a, . . . , 80-4a on the wafer 14. Thereafter, asshown in FIG. 12B, exposure is performed with respect to the areas80-1b, 80-2b, . . . , 80-4b on the wafer 14 along a trace parallel tothe trace in FIG. 12A. Therefore, the main control system 23 controlsthe position of the wafer 14 such that the moving amount of the wafer 14corresponding to the trace 78 P of the exposure area 43 P in the −Ydirection in FIG. 10A becomes 2(LP−M)/β. According to this method, intwo exposure areas (e.g., the areas 80-1a and 80-1b), on the wafer 14,corresponding to the pattern area 75 of the reticle 7, the slit-likeexposure area 43 P is scanned in the same relative scanning direction.With this operation, the overlapping precision at the connection portion80c is improved.

In the first and second embodiments, since a refracting optical systemis used as the projection optical system 13, a rectangular illuminationarea is set on the reticle 7, as shown in FIGS. 5A and 7A. In contrastto this, the use of a projection optical system constituted by areflecting/refracting optical system using a concave mirror and the likewill provide advantageous effects in terms of aberrations and the like,especially as the wavelength of exposure light decreases. If thisreflecting/refracting optical system is used, since the aberrations of aconcave mirror or the like are reduced as the distance from the opticalaxis increases, the slit-like illumination area on the reticle 7 becomesan arcuated illumination area 81, as shown in FIG. 13A.

Assume that a width D of the illumination area 81 in the relativescanning direction is constant, and that the longitudinal direction, ofthe illumination area 81, which is perpendicular to the relativescanning direction is defined as the Y direction. In this case, theY-direction illuminance distribution of the illumination area 81 is setto be trapezoidal, as shown in FIG. 13B. That is, in two sides areas 81aand 81b of the illumination area 81 in the Y direction, the illuminanceslinearly decrease to 0. By setting such as illuminance distribution, theilluminance irregularity at the connection portion in a stitchingoperation can be reduced, similar to the second embodiment describedabove.

Consider a case where a regular hexagonal illumination area is set, as amodification of the second embodiment described above. The arrangementof this modification is the same as that of the second embodiment exceptfor the shape of an illumination area.

In the modification, in the first and second wafer scanning operations,the wafer is set at the same X-direction position when a pulse lasersource performs pulse emission. More specifically, as shown in FIG. 16A,the X-direction positions of an exposure point P9 which are set whenpulse emission is performed in the first wafer scanning operation aredefined as positions 8, and the X-direction positions of an exposurepoint P9 which are set when pulse emission is performed in the secondwafer scanning operation are defined as positions 12. In this case, amain control system 23 controls the timing of pulse emission through alaser source control system 51 to make the positions 12 and 8 coincidewith each other. As shown in FIG. 16A, there are five positions 8 insidean area 3a, and three positions 12 inside an area 3b. Therefore, withthe two slit scanning exposure operations, energy corresponding to atotal of eight pulses is radiated on the exposure point P9.

FIG. 16B shows a case where the pulse emission timings in the first andsecond scanning operations are shifted from those in the case shown inFIG. 16A in the X-direction by ΔL/2. Referring to FIG. 16B, assume thatthe X-direction positions of an exposure point P9 which are set whenpulse emission is performed in the first wafer scanning operation aredefined as positions 10, and the X-direction positions of the exposurepoint P9 which are set when pulse emission is performed in the secondwafer scanning operation are defined as positions 13. In this case, thewafer is also set at the same X-direction position when the pulse lasersource performs pulse emission in the first and second wafer scanningoperations. Since there are four positions 10 in an area 3a, and fourpositions 13 in an area 3b, energy corresponding to eight pulses isradiated on the exposure point P9 by the two slit scanning exposureoperations. In general, according to this modification, energycorresponding to eight pulses is radiated on each exposure point in aconnection portion 4 as well as an exposure point P0 in a non-connectionportion, thereby preventing illuminance irregularity.

Furthermore, in the modification, the pulse emission timing iscontrolled such that a wafer is set at the same X direction positionwhen the pulse laser source performs pulse emission in the first andsecond scanning operations. However, a wafer side, X stage 27 may becontrolled.

In the second embodiment and its modification, a stitching operationusing one reticle has been described. However, a plurality of reticlesmay be placed on the same reticle stage, and scanning exposure may berepeatedly performed while the reticles are interchanged with each otherin a stitching operation. In addition, the reticle stage in the secondembodiment and its modification may be constituted by a reticle sidescanning stage and a reticle side fine adjustment stage, as in the caseof the reticle stage system in the first embodiment.

The present invention is not limited to the first and second embodimentsdescribed above, and various changes and modifications can be madewithout departing from the scope and spirit of the invention.

1. An exposure apparatus for radiating exposure light on a predeterminedillumination area on a mask on which a pattern to be transferred isformed, and exposing the pattern on a photosensitive substrate,comprising: a scanning system for synchronously scanning the mask andthe photosensitive substrate in a predetermined first direction of theillumination area while maintaining a predetermined speed ratio; and anillumination condition setting portion for setting the illumination areato be rectangular, and letting a light intensity distribution of theillumination area in a second direction substantially perpendicular tothe first direction have a trapezoidal shape so that a middle portion ofthe distribution exhibits a substantially constant light intensity, andtwo side portions of the distribution exhibit a gradually decreasinglight intensity.
 2. An apparatus according to claim 1, wherein saidscanning system scans the mask and the photosensitive substrate at leasttwice in the first direction, and further comprising a substrate movingsystem for moving the photosensitive substrate in the second directionwhile first and second scanning operations with respect to the mask andthe photosensitive substrate are performed by said scanning system. 3.An apparatus according to claim 2, further comprising a mask movingsystem for moving the mask in the second direction while first andsecond scanning operations with respect to the mask and thephotosensitive substrate are performed by said scanning system.
 4. Anapparatus according to claim 2, further comprising: storage portion forstoring a relative positional difference between the mask and thephotosensitive substrate when the mask and the photosensitive substrateare to be synchronously scanned in the first direction; and a controllerfor controlling a position of at least of one of the mask and thephotosensitive substrate such that the relative positional difference inthe first scanning operation with respect to the mask and thephotosensitive substrate coincides with that in the second scanningoperation.
 5. An apparatus according to claim 2 wherein saidillumination condition setting portion determines a length M of each ofthe side portions, of the illumination area, in which the lightintensity gradually decreases, in the second direction so as toestablishM=(n·LP−LT)/(n+1) where n is an integer of not less than one, LP is alength of an illumination area on the mask in the second direction, andLT is a width of a pattern area, formed on the mask, in the seconddirection.
 6. An apparatus according to claim 5, further comprising aprojection optical system for projecting an image of a pattern of themask, irradiated with the exposure light, onto the photosensitivesubstrate at a projecting magnification β, and wherein a moving amountof the photosensitive substrate moved by said substrate moving system inthe second direction is defined asn·(LP−M)/β
 7. A projection exposure apparatus comprising: a pulse lightsource for pulse-emitting exposure light; an illumination optical systemfor illuminating a predetermined illumination area on a mask, on which apattern to be transferred is formed, with the exposure light; aprojection optical system for projecting an image of the pattern,irradiated with the exposure light, onto a photosensitive substrate; ascanning system for synchronously scanning the mask and thephotosensitive substrate at least twice in a predetermined firstdirection of the illumination area while maintaining a predeterminedspeed ratio; a substrate moving system for moving the photosensitivesubstrate in a second direction substantially perpendicular to the firstdirection while first and second scanning operations with respect to themask and the photosensitive substrate are performed by said scanningsystem; and a controller for controlling at least one of said pulselight source and said scanning system such that a position of thephotosensitive substrate in the first direction at the time when saidpulse light source performs pulse emission, in the first scanningoperation with respect to the photosensitive substrate and the maskcoincides with that in the second scanning operation.
 8. An apparatusaccording to claim 7, wherein said controller includes a positionstorage portion for detecting a position of the photosensitive substratein the first direction when said pulse light source performs pulseemission, and storing data indicating the position, and controls one ofsaid pulse light source and said synchronous scanning means on the basisof the stored data indicating the position of the photosensitivesubstrate.
 9. A scanning exposure apparatus comprising: a scanningsystem for synchronously scanning a mask and a photosensitive substratefor scanning exposure; and an adjusting system for moving the mask todecrease a positional deviation between the mask and the substrate,independently of scanning of the mask which is performed by saidscanning system, during the scanning exposure.
 10. An apparatusaccording to claim 9, further comprising: a projection optical systemfor projecting a pattern image of the mask onto the substrate; andwherein said scanning system includes a mask stage for scanning the maskin a direction perpendicular to an optical axis of said projectionoptical system and a substrate stage for scanning the substrate in thedirection perpendicular to the optical axis, and causes the mask stageand the substrate stage to scan at a speed ratio corresponding to aprojecting magnification of said projection optical system.
 11. Anapparatus according to claim 10, wherein said adjusting system includesa finely movable stage for relatively moving the mask on said mask stageand a driving member for finely driving said finely movable stage in thedirection perpendicular to said optical axis.
 12. An apparatus accordingto claim 11, further comprising: a first measuring system for measuringa position of the mask within a plane perpendicular to said opticalaxis; and a second measuring system for measuring a position of thesubstrate within a plane perpendicular to said optical axis, and whereinsaid adjusting system includes a controller for controlling the drivingmember in accordance with signals from said first and second measuringsystems.
 13. An apparatus according to claim 12, wherein said firstmeasuring system includes a rotational angle detecting device fordetecting a rotational angle of the mask within the plane perpendicularto said optical axis.
 14. An apparatus according to claim 13, whereinsaid finely movable stage includes a mirror having a reflecting surfacesubstantially perpendicular to said plane, and said first measuringsystem includes an interferometer for radiating a light beam onto saidreflecting surface and receiving the light beam reflected by saidreflecting surface.
 15. A scanning exposure apparatus for projecting apattern image of a mask onto a sensitive plate through a projectionoptical system in a scanning manner, the exposure apparatus comprising:(a) a plate stage for scanning the plate in at least one-dimensionaldirection under said projection optical system for the scanningexposure; (b) a first mask stage for scanning the mask in at least saidone-dimensional direction above said projection optical system for thescanning exposure; (c) a second mask stage for finely moving the mask onsaid first mask stage in each of translational and rotationaldirections; (d) a first driving system for synchronously driving saidplate stage and said first mask stage with a predetermined velocityratio for the scanning exposure; (e) a detecting system for detecting apositional deviation amount between the mask and the plate in a realtime manner during the scanning exposure; and (f) a second drivingsystem for driving said second mask stage to decrease the detecteddeviation amount during the scanning exposure.
 16. The scanning exposureapparatus according to claim 15, wherein said detecting system includesa first measuring unit to detect a relative translational deviationamount between the mask and the plate and a second measuring unit todetect a relative rotational deviation amount between the mask and theplate.
 17. The scanning exposure apparatus according to claim 16,wherein said second drive system includes a first actuator unit forfinely moving said second mask stage in said one-dimensional scanningdirection and in a cross direction of said scanning direction based onsaid translational deviation amount.
 18. The scanning exposure apparatusaccording to claim 16, wherein said second drive system includes asecond actuator unit for finely rotating said second mask stage about apredetermined point on the mask based on said rotational deviationamount.
 19. The scanning exposure apparatus according to claim 18,wherein said predetermined point on the mask is changed in saidone-dimensional scanning direction according to the scanning position ofthe mask.
 20. The scanning exposure apparatus according to claim 16,wherein said first and second measuring units include a mask sideinterferometer system for measuring a coordinate position and arotational angle of the mask and a plate side interferometer system formeasuring a coordinate position and a rotational angle of the plate. 21.The scanning exposure apparatus according to claim 15, wherein each ofsaid plate stage and said first mask stage is linearly movable in saidone-dimensional scanning direction by restraining of respective linearair-guide structures.
 22. The scanning exposure apparatus according toclaim 21, wherein said first driving system includes a mask side linearmotor for driving said first mask stage guided by the correspondinglinear air-guide structure and a plate side linear motor for drivingsaid plate stage guided by the corresponding linear air-guide structure.23. A scanning exposure apparatus for projecting a pattern image of amask onto a sensitive plate through a projection optical system in ascanning manner, the exposure apparatus comprising: (a) a plate stagefor moving the plate in at least one-dimensional direction under saidprojection optical system which has an imaging reduction ratio 1/β; (b)a first mask stage for moving the mask in at least said one-dimensionaldirection above said projection optical system; (c) a second mask stagefor finely moving the mask on said first mask stage in each oftranslational and rotational direction; (d) an illuminating system forirradiating the mask with a radiation having a slit shaped distributionelongated perpendicular to said one-dimensional direction on the mask inorder to project a slit shaped partial pattern image of the mask ontothe plate through said projection optical system; (e) a first drivingsystem for synchronously, relatively driving said plate stage and firstmask stage with a velocity ratio B for the scanning exposure of theplate by said slit shaped partial pattern image of the mask; (f) adetecting system for detecting a deviation amount from an idealpositional relation of the mask and the plate occurring at a term of thescanning exposure; and (g) a second driving system for driving saidsecond mask stage to correct the deviation during the scanning exposurewhen said detected deviation amount is out of a predetermined tolerance.24. The scanning exposure apparatus according to claim 23, wherein saiddetecting system includes a first measuring system to detect atranslational deviation amount from said ideal positional relation ofthe mask and the plate and a second measuring system to detect arotational deviation amount from said ideal positional relation of themask and the plate.
 25. The scanning exposure apparatus according toclaim 24, wherein said second drive system includes a first actuatorsystem for finely moving said second mask stage in said one-dimensionalscanning direction and a cross direction thereof based on saidtranslational deviation amount.
 26. The scanning exposure apparatusaccording to claim 24, wherein said second drive system includes asecond actuator system for finely rotating said second mask stage abouta predetermined point on the mask based on said rotational deviationamount.
 27. The scanning exposure apparatus according to claim 26,wherein said predetermined point on the mask is changed in saidone-dimensional scanning direction according to the scanning position ofthe mask.
 28. The scanning exposure apparatus according to claim 23,wherein said first driving system includes a mask side linear motor fordriving said first mask stage supported by an air-guide structure and aplate side linear motor for driving said plate stage supported by anair-guide structure.
 29. A scanning exposure apparatus for projecting apattern image of a mask onto a sensitive plate through a projectionsystem having a predetermined magnification ratio in a scanning manner,the apparatus comprising: (a) a scanning system for synchronously,relatively scanning the mask and the plate with respect to a projectionfield of said projection system at a velocity ratio corresponding tosaid magnification ratio during the scanning exposure; (b) a finelymovable stage provided on said scanning system for finely moving themask relative to said scanning system in each of translational androtational directions; (c) a detecting system for detecting a positionaldeviation amount between an ideal positional relation and an actualpositional relation of the mask and the plate during the scanningexposure; and (d) a control system for driving said finely movable stagebased on said detected deviation amount in order to decrease thepositional deviation of the mask and the plate.
 30. A scanning exposuremethod in which a pattern area of a mask is transferred onto a sensitiveplate through a projection optical system in a scanning manner, themethod comprising the steps of: (a) irradiating the mask with aradiation having a slit shaped intensity distribution in order toproject a slit image portion of said pattern area of the mask toward theplate through said projection optical system; (b) synchrouously scanningeach of the mask and the plate relative to said projection opticalsystem in a scanning direction perpendicular to a longitudinal directionof said slit image portion at a predetermined velocity ratio by using ascanning mechanism for the scanning exposure; (c) detecting a deviationvalue between an ideal positional relation and an actual positionalrelation of the mask and the plate at a term of the scanning exposure;and (d) correcting a position of the mask determined by said scanningmechanism so as to decrease said detected deviation value by using afine moving mechanism provided on said scanning mechanism at the term ofthe scanning exposure.
 31. The scanning exposure method according toclaim 30, wherein said detecting step includes detecting a relativerotational deviation between the mask and the plate and said fine movingmechanism finely rotates the mask to decrease said rotational deviation.32. The scanning exposure method according to claim 31, wherein saidrelative rotational deviation is detected by using a mask sideinterferometer system and a plate side interferometer system.
 33. Ascanning exposure method in which a pattern area of a mask istransferred onto a sensitive plate through a projection system in ascanning manner, the method comprising the steps of: (a) irradiating themask with a radiation in order to project an image portion of saidpattern area of the mask onto the plate through said projection system;(b) synchronously scanning each of the mask and the plate relative tosaid projection system in a scanning direction at a predeterminedvelocity ratio by using a scanning mechanism for the scanning exposure;(c) detecting a deviation between an ideal positional relation and anactual positional relation of the mask and the plate at a term of thescanning exposure; and (d) correcting a position of the mask determinedby said scanning mechanism for decreasing said detected deviation byusing a fine moving mechanism provided on said scanning mechanism at theterm of the scanning exposure.
 34. A scanning exposure apparatus forprojecting a pattern image of a mask onto a sensitive plate through aprojection system in a scanning manner, the exposure apparatuscomprising: (a) a plate stage for moving the plate under said projectionsystem in an X direction for the scanning exposure and in a Y directionperpendicular to the X direction; (b) a first mask stage for moving themask in the X direction for the scanning exposure above said projectionsystem; (c) a second mask stage for finely moving the mask on said firstmask stage in each of translational and rotational directions; (d) firstdriving means for synchronously driving each of said plate stage andsaid first mask stage with a predetermined velocity ratio in the Xdirection during the scanning exposure; and (e) second driving means fordriving said plate stage and said second mask stage to maintain atranslational relation of the mask and plate in the Y direction and fordriving said second mask stage to maintain a relative rotationalrelation of the mask and the plate, during the scanning exposure.
 35. Ascanning exposure method in which in synchronism with movement of afirst object formed with a predetermined pattern a second object ismoved, thereby exposing sequentially a plurality of defined regions onsaid second object, comprising: effecting an exposure onto one of theplurality of the defined regions on said second object while moving saidsecond object in a predetermined direction, and after finishing theexposure, moving said second object in a direction perpendicular to saidpredetermined direction while moving said second object in a directionparallel to said predetermined direction.
 36. A scanning exposure methodin which in synchronism with movement of a first object formed with apredetermined pattern a second object is moved, thereby exposingsequentially a plurality of defined regions on said second object,comprising: effecting an exposure onto one of the plurality of thedefined regions on said second object while moving said second object ina predetermined direction, and after finishing the exposure,accelerating said second object in a direction intersecting with saidpredetermined direction while decelerating said second object in saidpredetermined direction.
 37. A scanning exposure method in which insynchronism with movement of a first object formed with a predeterminedpattern a second object is moved, thereby exposing sequentially aplurality of defined regions on said second object, comprising: a firststep of effecting an exposure onto one of the plurality of definedregions on said second object while moving said second object in apredetermined direction, a second step of decelerating said secondobject in said predetermined direction after finishing the exposure, athird step of accelerating said second object in a reverse direction tosaid predetermined direction after said second step, and a fourth stepof accelerating and decelerating said second object in a directionintersecting with said predetermined direction during said second stepand said third step.
 38. A scanning exposure method in which insynchronism with movement of a first object formed with a predeterminedpattern a second object is moved, thereby exposing sequentially aplurality of defined regions on said second object, comprising:effecting an exposure onto one of the plurality of defined regions onsaid second object while moving said first object in a first directionand moving said second object in a second direction corresponding tosaid first direction, and after finishing the exposure, moving saidsecond object in a direction parallel and perpendicular to said seconddirection simultaneously while decelerating said first object in saidfirst direction.
 39. A scanning exposure method in which in synchronismwith movement of a first object formed with a predetermined pattern asecond object is moved, thereby exposing sequentially a plurality ofdefined regions on said second object, comprising: a first step ofeffecting an exposure onto one of the plurality of defined regions onsaid second object while moving said first object in a first directionand moving said second object in a second direction corresponding tosaid first direction, and a second step of decelerating said secondobject in said second direction after finishing the first step, a thirdstep of accelerating said second object in a reverse direction to saidsecond direction after said second step, and a fourth step ofdecelerating said first object and setting said first object to areference position during said second step and said third step.
 40. Ascanning exposure method in which in synchronism with movement of afirst object formed with a predetermined pattern a second object ismoved, thereby exposing sequentially a plurality of defined regions onsaid second object, comprising: effecting an exposure onto one of theplurality of defined regions on said second object while moving saidsecond object in a predetermined direction, and after finishing theexposure, starting accelerating said second object in a reversedirection to said predetermined direction for preparing a scanningexposure onto a next defined region while moving said second object in adirection intersecting with said predetermined direction.
 41. A scanningtype exposure apparatus in which in synchronism with moving a firstobject in a first direction, a second object is moved in a seconddirection, thereby exposing sequentially each of a plurality of definedregions on said second object, comprising: a projection optical systemwhich is disposed in an optical path of an exposure beam, said firstobject being provided on one side of the projection optical system, saidsecond object being provided on the other side of the projection opticalsystem, and an image of a pattern formed on said first object beingprojected onto said second object by the projection optical system; afirst movable stage which holds said first object, at least a part ofthe first movable stage being disposed on the one side of the projectionoptical system; a second movable stage which holds said second object,at least a part of the second movable stage being disposed on the otherside of the projection optical system; a first interferometer systemwhich outputs positional information of said first movable stage, thefirst interferometer system being optically connected to said firstmovable stage; a second interferometer system which outputs positionalinformation of said second movable stage, the second interferometersystem being optically connected to said second movable stage; a firstdrive mechanism, functionally connected to the first movable stage,which moves said first movable stage in said first direction; a seconddrive mechanism, functionally connected to the second stage, which movessaid second movable stage in said second direction; and a controllerfunctionally connected to said first interferometer system, said secondinterferometer system, said first drive mechanism and said second drivemechanism, which converts positional information in said seconddirection of said second movable stage outputted from said secondinterferometer system to first speed information and speed controls saidsecond drive mechanism so that said first speed information maycorrespond to a constant speed V, and which converts positionalinformation in said first direction of said first movable stageoutputted from said first interferometer system to second speedinformation and speed controls said first drive mechanism so that saidsecond speed information may correspond to a constant speed V/β, where βis a projection magnification of the image of the pattern on said firstobject projected by said projection optical system.